The use of laryngeal mask airway devices in ambulatory anesthesia

Effects of fentanyl administration before induction of anesthesia and placement of the Laryngeal Mask Airway: a randomized, placebo-controlled trial

STUDY OBJECTIVE

To assess the effects of fentanyl administered before induction of anesthesia on movement and airway responses during desflurane anesthesia via the Laryngeal Mask Airway (LMA).

DESIGN

Randomized, double-blinded, controlled trial.

STUDY SETTING

Tertiary-care academic center.

PATIENTS

100 adult, ASA physical status 1, 2, and 3 patients undergoing ambulatory surgery.

INTERVENTIONS

Patients were administered fentanyl 1 μg/kg (n=51) or saline (n=49) 3 to 5 minutes before induction with propofol 2-2.5 mg/kg intravenously (IV), followed by LMA placement. Anesthesia was maintained with desflurane titrated to a bispectral index (BIS) of 50-60 and 50% nitrous oxide in oxygen, and fentanyl 25 μg boluses were titrated to respiratory rate.

MEASUREMENTS

Apnea occurrence and duration of manual ventilation, as well as frequency and severity of movement, coughing, breath holding, and laryngospasm were recorded.

MAIN RESULTS

Two patients in each group were excluded from analysis. The fentanyl pretreatment group had a higher frequency of apnea (94% vs 64%; P=0.0003) and longer duration of manual ventilation (3 [interquartile range (IQR), 1.5-5] min vs 1 [0-1.5] min; P<0.0001) at induction. In contrast, the fentanyl pretreatment group had a lower frequency of movements (16% vs 51%;P=0.0001). The rates of intraoperative breath holding (6.1% vs 8.5%) and laryngospasm (2% vs 4.3%) in the two groups were similar. All subjects experiencing laryngospasm were smokers. Adjusting for smoking status did not affect the differences noted in apnea, duration of manual ventilation, or movement between groups; however, coughing occurrence was statistically higher in the placebo group (P=0.043).

CONCLUSIONS

Preinduction fentanyl increased the frequency of apnea at induction and duration of manual ventilation, but reduced the frequency of movements. In addition, it reduced intraoperative coughing in smokers.

Inhalational techniques in ambulatory anesthesia

In the current health care environment, anesthesia practitioners are frequently required to reevaluate their practice to be more efficient and cost-effective. Although IV induction with propofol and inhalational induction with sevoflurane are both suitable techniques for outpatients, patients prefer IV induction. Maintenance of anesthesia with the newer inhaled anesthetics (ie, desflurane and sevoflurane) provide for a rapid early recovery as compared with infusion of propofol (ie, TIVA), while allowing easy titratability of anesthetic depth. Titration of hypnotic sedatives using BIS monitoring may reduce the time to awakening and thereby may facilitate fast tracking (ie, bypassing the PACU) and reduce hospital stay. Inhalational anesthesia is associated with a higher incidence of PONV, but no differences have been demonstrated with respect to late recovery (eg, PACU stay and home readiness). Although clinical differences between desflurane and sevoflurane appear to be small, desflurane may be associated with faster emergence, particularly in elderly and morbidly obese patients. Balanced anesthesia with IV propofol induction and inhalation anesthesia with N2O for maintenance, and an LMA for airway management, may be an optimal technique for ambulatory surgery. Inhalational anesthesia may have an economic advantage over a TIVA technique.